As broadly known, over the recent years, a variety of communication standards having higher communication speeds such as Ethernet (trademark of Xerox Corp. in U.S.A.) or Fibre Channel have been developed, and there have been an increased number of computers each mounted with a communication adaptor (an expansion card functioning as a communication interface) pursuant to these types of communication standards.
The normal communication adaptor is contrived to interrupt a CPU [Central Processing Unit] via a PCI [Peripheral Components Interconnect] bus and a host bridge each time a process (transmission or reception) related to one piece of data is completed. Therefore, an interrupt count per, unit time when the communication adaptor interrupts the CPU rises as the communication speed increases. Then, if a plurality of communication adaptors operating fast is mounted in the computer, such a problem arises that a considerable load is applied to the CPU.                [Patent Document 1] International Publication WO03/063002        [Patent Document 2] Japanese Laid-Open Patent Publication No. 2002-023961        [Patent Document 3] Japanese Laid-Open Patent Publication No. H11-015800        [Patent Document 4] Japanese Laid-Open Patent Publication No. S53-145536        [Patent Document 5] Japanese Laid-Open Patent Publication No. S52-047648        